EEVEE Alpha Blend Sorting problem - discussion for solutions

Hai hai everyone :smiley:,

so with the EEVEE rewrite underway (yay), i was thinking of opening a discussion to possible solutions to Alpha Blending’s sorting issue (if they even exist ? :thinking:), it seemed like the perfect opportune time to do so.

(For those who don’t know, this is a issue when transparency is turned on with “show backfaces” also turned on, you get these square artefacts with the Alpha Blend, picture borrowed from TimParaxade)

Since i know little on this problem in detail other than that it’s a sorting problem, i was wondering if anyone knows of a solution to this problem ?
I’m aware that Blender is not the only program with this problem, apparently all programs suffer from this error.

Material Settings — Blender Manual
:anchor: T59803 [Shading] Backside obsures frontside when Alpha Blend is on (blender.org)
:anchor: T62559 Eevee Alpha Blend Depth Error (blender.org)

My reason for this discussion is that although Alpha Hash gives a good solution, its has the issue of being very noisy with few samples which require denoising, which in the viewport is insanely distracting. So i was wondering if its possible to “Fix” Alpha Blend to give us a desired result without any noise.

Thank you for your time peeps :grinning_face_with_smiling_eyes:

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This issue is so old it exists in a game from 2004 even.

Which begs the question all the more, does a solution exist ?

Or has anyone at least an idea for a solution :grinning_face_with_smiling_eyes:

I think there is probably a solution

I recall the game Metal Gear Solid 5 having dog fur transparency that looked great and had no sorting issues despite the many laters of fur.

(I hope it was a better Alpha Blend and not maybe Alpha Clip lol, but it looked smooth)

Update:

I think it might just be a sort of Alpha Hash lol
It looks smoother in-game / a meter away or perhaps there’s some kind of blur filter on it like Anti-Alias

Fascinating, i never knew that this was even a opened topic from the MGS devs,

i wish more people would pitch in on this topic :smiley: